1. Field of the Invention
The invention relates to a twelve-pulse converter system in which two three-phase converter bridges are adapted to be connected to respective converter transformers, are connected in series on their DC sides and include bridge sections, several of whose valves are arranged one on top of the other in tower-like fashion.
2. Description of the Prior Art
A prior art twelve-pulse converter system comprises two three-phase converter bridges, one of which is connected to a Y-connected transformer and the other of which is connected to a delta-connected transformer. The converter bridges are connected on their DC sides in series and each converter bridge includes separately mounted valves for the individual converter phases. More particularly, the four converter valves of the two bridges associated with each given phase are arranged one on top of the other with the two converter valves associated with one bridge arranged at the bottom and connected to one of the above-mentioned transformers and the two converter valves associated with the other bridge disposed at the top and connected to the other of the above-mentioned transformers.
The aforesaid prior art converter has various disadvantages. Because the valves associated with different phases are arranged in separate towers, a large base area is required. In addition, appropriate safety distances must be maintained between the individual valve towers and the housing in which the valve towers are arranged. This means that the housing must be made relatively large. Furthermore, since each valve tower must be connected to both transformers, the AC leads connecting the transformers to the valve towers must cross in two planes on top of each other. This requires a considerable amount of apparatus for the disposition of the leads.
It is an object of the present invention to provide an improved twelve-pulse converter system which requires a minimum of base area, a relatively small housing and, furthermore, includes a simple arrangement for the leads coupling the converter valves to the transformers.